Immunoprecipitation and polyacrylamide gel electrophoresis techniques have been used to determine the degree to which leukemia virus genetic information associated with different isolates and variants of the Moloney sarcoma genome is expressed in nonproducer transformed cells. Messenger RNAs from cells nonproductively transformed by the Moloney sarcoma virus have been used to program an in vitro translation system prepared from rabbit reticulocytes. Size fractionation of these cellular RNAs, in conjunction with hybrid arrest translation experiments, may enable identification of transforming proteins coded by the sarcoma virus genome.